public class ExpressDelivery {
    private String sender;
    private String receiver;
    private String location;
    private String coordinates;

    public ExpressDelivery(String sender, String receiver) {
        this.sender = sender;
        this.receiver = receiver;
    }

    public void beforeDelivery() {
        System.out.println("发货前准备");
    }

    public void deliver() {
        System.out.println("发货成功");
    }

    public void unload() {
        System.out.println("卸货完成");
    }
}